Ethylene is oxidized under the action of the silver catalyst to mainly produce ethylene oxide, which is accompanied by the side reaction to produce carbon dioxide and water. The main properties of the silver catalyst include activity, selectivity and stability. The activity is reflected by the reaction temperature at which ethylene oxide is produced with a certain reaction load. The lower the reaction temperature is, the higher the catalyst activity is. The selectivity means the ratio of the mole of ethylene that converts to ethylene oxide to the total mole of ethylene that takes part in the reaction. The stability is reflected by the rate at which the activity or selectivity drops. The lower the dropping rate is, the better the catalyst stability is.
The silver catalyst having high activity, high selectivity and good stability during the production of ethylene oxide by the oxidization of ethylene can improve the economical benefit remarkably. Thus, it is a main research object of the silver catalyst to make a silver catalyst having high activity, high selectivity and good stability.
The silver catalyst preparation method in the prior art comprises the steps of preparing porous carrier such as alumina and applying active components and promoters onto said porous carrier.
Some new silver catalyst carrier technologies are reported in recent years; for example, see the Chinese patent application publication Nos. CN1511632A, CN1400048A and CN1400053A.